There are three different -ed sounds in English

 For example, the -ed in "walked" sounds different than in "called".

 -ed can sound like /t/ or /d/ or /ed/

/t/ has a puff of air and sounds like this.

/d/ has no puff of air and sounds like this.

/ed/ sounds like you are pronouncing "ed" separately.

Put your hand in front of your mouth and try to pronounce /t/ and /d/. 

When you say /t/, you should feel air on your hand.

When you say /d/, there should be almost no air on your hand.

If the verb stem ends with a puff of air, you need the /t/ sound

Put your hand in front of your mouth and say “walk”.

Do you feel the puff of air?  You should. "walked" has the /t/ sound.

 If there is no puff of air, you need the /d/ sound

 Put your hand in front of your mouth and say “call”.

 You should not feel air on your hand.  "called" has the /d/ sound.

 If a word ends in "d" or "t", you need the /ed/ sound.

 "needed" has the /ed/ sound.  It sounds you are saying "need" and then "ed".

Please listen to the video to hear more pronunciation of -ed!

I hope this information has been useful for you to improve your pronunciation in English!

Please be sure to visit my profile. Thank you!  

Sarah